The present invention relates to nuclear reactor systems and refers more particularly to a nuclear reactor pressure vessel for use in large size water reactor systems, more particularly to such systems as represent size and capacity ratings not readily possible when employing reactor pressure vessel types as heretofore commonly used.
The evolution of nuclear reactor systems of the water reactor type has led to development of such systems in the 1000 megawatt plus range and utilization of reactor pressure vessels wherein operating pressure is about 1000 p.s.i. These reactor vessels have reached an internal diameter of about 7 meters. Manufacture of vessels of this size involves special fabrication requirements not easily met and especially since fabricators capable of fulfilling such manufacturing task are few. Also with a practical steel vessel diameter limitation of about 7 meters, there still is presented the problem of finding available surface space on a vessel to effect pass through of the many devices and appurtenant components which must be fixed on the vessel, such components including, inter alia, reactor core control rods, piping, instrumentation, cooling lines etc. This surface space requirement has led to penetration of the vessel on two or more sides, e.g., head and wall and at numbers of points. Because of this, the entire pressure vessel must be placed within a containment structure. In any event and even though the drawbacks attending limited pressure vessel size have to an extent been mitigated, the result is nonetheless, a maze of closely coupled and arranged structure having the attribute of undesirable complexity especially since larger available space and structure to accept essential components leads to more optimized installations. And not the least shortcoming of present reactor vessel designs is the inherent limitation such present to increasing system capacity.
Accordingly, it is believed a new approach to reactor pressure vessel sizing and construction which will allow tandem progress with other system enhancements is desirable and indeed, essential.